1. Field of the Invention
This invention relates to children play yard, and more particularly to a foldable children play-yard frame structure, which may including curve peripheral sides.
2. Related Art
Various prior art foldable children play-yards are known. Two examples of such known prior art are disclosed in U.S. Pat. Nos. 4,811,437 and 5,446,936. These prior art play-yards generally incorporate a rectangular frame structure having a front side, a back side and two opposite lateral sides. The frame structure has four corner upright support legs to provide structural support for the play-yard. The support legs are connected to an upper frame member by L-shape corner connectors. These L-shape connectors have two perpendicular body segments each having vertically spaced apart internal walls to form downward-facing internal open channels. The L-shape corner connectors are rigidly mounted to the top of the support legs.
The upper frame member is constructed of four pair of elongated straight tubular side rails, which form the four sides of the rectangular frame and define the upper perimeter of the play-yard. On the front and the back sides of the rectangular frame, the two side rails are secured in the internal channels of the L-shape connectors of the adjacent support legs. The side rails are pivotally connected to the walls of the L-shape connectors to enable the side rails to rotate on a vertical plane that is defined by that side of the frame. The other ends of the side rails are pivotally connected to a rail connector to enable the side rails to rotate and folded into a V-shape configuration along the same vertical plane.
On the lateral sides of the play-yard, the side rails are similarly pivotally connected to the other perpendicular sides of the L-shape connectors and to the rail connectors to enable the side rails to be rotated on the vertical planes as defined by the respective lateral sides.
The frame structures of the prior art also have a lower frame member which is pivotally connected to the lower portions of the of the upright support legs and is foldable during retraction of the play-yard from an extended configuration to a folded configuration. The lower frame member incorporates a central hub pivotally connected to four radially extending straight tubular members that are pivotally connector to the lower portion of the upright legs.
In the prior art design, the rail connectors each has a releasable locking mechanism to secure the side rails in a straight line when the play-yard is fully deployed. When the lock is released, the play-yard can be retracted by rotating the side rails on the four rectangular sides on their respective vertical planes while the upright legs are drawn together. In the folded configuration, the side rails would generally assume a V-shape relationship tucked on the underside the L-shape connectors between the parallel upright legs.
While the prior art design provides for a foldable children play-yard, there are a number of drawbacks. In general, the prior art design is limited to a rectangular structure where the square corners and straight lines of the structures often lack aesthetic appeals to those who would prefer a more streamlined structural configuration having curves and non-straight line designs. Furthermore, as disclosed in the afore-referenced United States patents, although the intended objective of the prior art design is to provide a foldable children play-yard having the apparent capability of folding a rectangular frame structure into a compact configuration with a square end profile, the folding operation can be challenging in practice.
In the prior art frame structures, the footprint of the play-yard is defined by the support legs arranged in a spaced apart rectangular relationship when the play-yard is deployed. In the deployed configuration, the tubular members of the lower frame are oriented in pairs to bisect in a non-perpendicular relationship. When the play-yard is retracted, the support legs are collected side by side into a folded configuration having a square end profile. As the rectangular frame structure is folded, the individual lower frame tubular members would experience an internal stress. This is due to lateral displacements of the lower frame tubular members necessitated by the change of the rectangular footprint to the square footprint of the play-yard structure from the deployed to the folded configuration. Such internal stress is transmitted to the support legs and the corner connectors and other parts of the frame structure making the folding operation difficult or inconvenient.